Thread-rolling tool or appliance



Aug. 8, 1944. T. K. AFFLECK l THREAD-ROLLING TOOL OR APPLIANCE FiledDeo. 30, 1942 Patented Aug. 8,1944

THREAD-ROLLING Tool. R APPLIANCE Theodore King Afileck, London, England,as-

signor to Acton Boet and Fine Threads Limited, London, England, acompany of Great Britain Application December 30, 1942, Serial No.470,653 In Great Britain January 5, 1942 3 Claims.

This invention has reference to tools or appliances for use in theformation of screw-threads on revolving work-pieces, such devices beingof the kind comprising a, pair of spaced threaded rolls rotatablymounted in a holder or carrier and adapted to be pressed into rollingcontact with the work-peice so as to roll a thread thereon, and theholder being fed forward until the axes of the rolls lie atdiametrically opposite sides of the work-piece axis. Since both rollsco-opcrate in the formation of the same thread, it is necessary thatthey must bear a certain angular relationship to each other to obtainthe correct thread form, and the present invention is concerned withproviding the necessary means whereby after each operation the rolls areautomatically returned to rest in that angular relationship so that theyco-operate correctly on making contact With the next work-piece.

It has heretofore been proposed to preserve the correct angularpositions of the rolls by means of positive gearing between theirspindles, but such an arrangement is impracticable for the reason thatboth rolls do not retain the same linear velocity in relation to theworkpiece during the period of time between the instant when they firstmake contact with the latter and their arrival at the end of theirforward movement when they lie on diametrically opposite sides of theWork-piece, owing to the fact that the forward displacement of the toolas a Whole during the period referred to has the effect of increasingthe linear velocity of the workpiece in relation to one roll anddecreasing it in relation to the other roll, vso that during such periodthe rolls are revolving at different speeds.

A thread-rolling device of the said kind, in accordance with the presentinvention, comprises gearing between one of the rolls and a rotatablemember associated with the second roll so that the irst roll and saidmember rotate at the same speed, a positive driving-connection betweensaid member and said second roll operative when the rolls are in theircorrect angular relationship for the commencement of a threadrollingoperation, means permitting said member to make a restricted angularmovement in relation to the second roll suiiicient to accommodate suchrelative roll-velocity differences as may occur in the circumstanceshereinbefore referred to, and a spring-connection between the member andthe second roll which serves to return the former to its said initialposition relative to the latter on withdrawal of the tool from theworkpiece.

The aforesaid member to which the first roll is geared may be looselyrotatable on the spindle of the second roll and the positivedriving-connection for said member mayconsists of a pair ofinter-engaging abutments respectively fixed to the spindle of the secondroll and to the member.

One form of thread-rolling device as constructed in accordance with theinvention is illustrated in, and is hereinafter described with referenceto, the accompanying drawing, of which Fig. 1 is a side elevation of thetool, Fig. 2 a section thereof taken on the line II-II of Fig. 1, andFig. 3 a detail section taken on the line III-III of Fig. 2. Figs. 4 and5 are fragmentary sectional views depicting the relative positions ofthe thread-rolls and the work-piece as the tool is in the act of beingbrought into engagement with the work-piece, and at the completion ofthe forward movement of the tool, respectively.

As will be seen from the drawing, the tool comprises a pair of threadedrolls I0, Il, which are keyed upon spindles I2, I3 rotatably mounted inspaced relationship in a block I4 which is pivotally supported upon thecarrier I5. The block I4 is bifurcated to enclose the rolls I0, IIbetween the portions I4I and |42. A spur Wheel I6 is fixed on thespindle I3 of the roll Il and an idler pinion I1 rotating on a fixedpivot I8 upon the block I4 transmits the rotary motion of the spindle I3to a second spur wheel I9 (of equal pitch diameter with the spur wheelI6) loose upon the spindle I2 of the roll I0. A disc 2U fixed upon thespindle I2 in close juxtaposition to the spur wheel I9 carries on itsface fixed stops 2| (Fig. 3) adapted to register with and abut againstsimilar stops 22 fixed to the adjacent face of the spur wheel I9, sothat in one direction of rotation of said disc 20 the spur'wheel I9 isdriven thereby through the abutment of said stops 2 I 22.

The necessity of permitting the rolls I0, Il to rotate at differentspeeds during the operation of moving the tool to the position on whichthe rolls lie on diametrically opposite sides of the workpiece will bebetter understood by reference to Figs. 4 and 5, in which the work-pieceis designated by the reference numeral 23. The directions of rotation ofthe work-piece 23 and the rolls I0, II are indicated by arrows, as alsois the direction of movement of the tool as a whole to perform thethread-rolling operation. It will be evident that during the period oftime occupied by forward displacement of the tool as a whole from theposition shown in Fig. 4, in which the 2 Y 1 rolls Il. II first makecontact with the workpiece 2l. to the position shown in Fig. 5. in whichsaid rolls lie on diametrically opposite sides oi the work-piece, thelinear velocity of the work.

in Fig. 5), it is withdrawn as speedily as possible for reasons wellunderstoodl in the art, but during any slight d well which may occur atthat position the loose spur wlieel I9 maintains its angularrelationship in advance of the disc 20. It will be evident that uponthe'withdrawal of the tool the rolls I0, I I will come to rest and inorder to ensure that the roll I9 which is associated with the loose spurwheel I9 shall immediately resume its correct angular relationship tothe roll Il, a coil spring 24 is arranged with its extremiiies anchoredrespectively to the disc and the loose spur wheel I9, said spring 2loperating to rotate the loose spur wheel I9 upon its spindle I2 untilthe stops 22 abut against the stops 2I upon the disc 20, and the partsare thus held in that position until the next operation has commencedand the loose spur wheel I9 again begins to advance upon the disc 20. ii

As in other forms of thread-rolling devices, provision is made for acertain longitudinal movement of the rolls I0, II in relation to thetool holder. In this case spring-pressed abutments are furnished at theends of the spindles carrying the thread-forming olls; at one endindividual springs 25, 2S bear against the extremities of the spindlesI2, I9, and at the other end a c'ommon spring strip 21 is mounted upon asupport 28 between the spindles I2, I3 with its extremities respectivelypressing against a washer 29 contacting the disc 20 and a shoulder 99 onthe spindle I9, the arrangement being such that the spindles and rollsare returned to their initial relative longitudinal position after anyendwise movement which may have occurred 'during theirollins operation.A

It will be apparent that the invention is applicable to al1 forms ofthread-rolling tools of the 5 kind specified, whatever may be, theproportion between the diameters of the thread-forming rolls I and thework-piece.

What I claimI as my invention and desire to secure by Letters Patent is:

l. In a machine for rolling screw threads, in combination, threadingrolls rotatable about parallel axes and laterally spaced apart so as toreceive between them a work piece to be threaded, and meansv associatedwith said rolls for main- 15 taining them in a predetermined angularrelatlonship when not engaging a work piece, and per` mitting said rollsto rotate relatively to each other when a. work piece is insertedbetween them, said means including a train oi' intermeshing gears,

'20- and a driving connection between one oi.' said gears and one oisaid rolls which prevents relative I rotation of said gear and roll inone direction andpermits restricted relative rotation oi' said gear androll in the opposite direction.

2. The combination set forth in claim 1 in which said driving connectionincludes interengaging stops and a resilient elementnormally maintainingsaid stops in contact but permitting them to separate when one roll iscaused to revolve at an 30 angular velocity greater than that of theother.

3. In a machine for rolling Iscrew threads, in combination, a base,parallel spindles rotatably mounted on said base, threading rollsmounted on said spindles, respectively, and positioned to re- 5 ceivebetween them a work piece to be threaded,

and mechanism connecting said spindles including gears of equal diametermounted on said spindles. respectively, one gear being ilxed, and theother rotatably mounted, on the associated spindle, an intermedate idlergear with which both of said first mentioned gears mesh, meanspositively connecting the rotatably mcunted gear to the asso- I ciatedspindle for simultaneous rotation in one direction, and resilient meansconnecting said last mentioned gear to the associated spindle permittinglimited angular movement of said gear and spindle in oppositedirections.

THEODORE KING AFFLECK.

CERTIFICATE oF CORRECTION. Patent No. 2,555,152. August 8, 191m.

THEODORE KING AFFLECK.

It vis hereby certified that error appears in the above numbered patentrequiring correction as follows: In the grantl,lines 2 and 13respectively, name of assignee, for "Action Boet and Fine IIhreadsLimited" read --Acton Bolt and Fine Threads Limited-f; lin the headingto the printed specification, line li, for "Acton Boet and Fine ThreadsLimited, read -I-Acton Bolt and Fine Threads Limited", as shown by therecord of assignments in this office; and that the said Letters' Patentshould be readwith this correction therein that the same may conform tothe record of the case in the Patent Office.

Signed and sealed this 26th day of September, A. D. 191114..

Leslie Frazer (S981) Acting Commissioner of Patents.

